Underwater soundscape transition bug?

It seems there is a bug in soundscapes underwater. Here's the example set-up:

You have two areas, separated by a long underwater tunnel. Each area has a loud and distinct soundscape. However, soundscapes (or at least soundscape proxies) have no effect when you see them underwater. It's as if line-of-sight tests fail.

Because of this, going from one area to another there is a jarring sound transition at the surface of the water, as you leave it. Depending on which direction you're going, the middle of the tunnel could sound like area A or area B. (You can test it with the soundscape_debug cvar.)

Is this just my machine? If not, has anybody managed a workaround that didn't involve forcing the player to surface early?

I was able to "push out" the loud soundscape I wanted to leave by forcing the player to swim through a trigger_soundscape, which activated an env_soundscape_triggerable, which in turn had duplicated settings for a "real" soundscape. (Why there isn't a triggerable proxy, I don't know.)

Swimming the other way, a separate trigger/soundscape pair was needed.